Caravan Misc. Knowledge

Question 1

How many fuel nozzles and when do they operate?

Answer 1

There are 14 simplex nozzles, 10 primary and 4 secondary. 10 operate throughout the starting regime, 4 after 30-35% Ng. Without the 4 secondary nozzles, the engine may hang at 30-35% Ng during start. For operations from normal idle through max power, all 14 nozzles operate

Question 2

What is the function of the GCU (generator control unit)?

Answer 2

The GCU provides voltage regulation, over-voltage protection, reverse current protection, voltage regulation and automatic starter cutoff when RPM reaches above 46% Ng.
Below 46%- acts as a starter
Above 46%- acts as a generator (starter switch off)

Question 3

How does the emergency power lever operate?

Answer 3

In the event of a pneumatic FCU failure (a decrease of Ng to approximately 48% at sea level, with the Ng percentage increasing with altitude), the emergency power lever is used to mechanically control the fuel supply to the engine.

Question 4

If you accidentally move the condition lever to cutoff when on the ground, what action should you take?

Answer 4

Do not attempt to reintroduce fuel as this could lead to an engine overheat. You should dry motor the engine to cool it down prior to attempting a normal start.

Question 5

What is the prop deice electrical draw cycle?

Answer 5

20-24 amps for 90 seconds, followed by no draw for 90 seconds

Question 6

How many igniters are in the engine and what is the NORM position for them?

Answer 6

2 igniters controlled by an ignition switch on the left side panel. NORM arms the igniters to turn on during the start cycle.

Question 7

Approximately how many gallons of Jet A in 100 pounds?

Answer 7

15 gallons per 100 pounds of fuel, or 6.7 lbs./gal

Question 8

What is meant by a hung start in a turbine engine?

Answer 8

A start in which ignition occurs but the engine does not accelerate to a self-sustaining speed. (Battery, nozzle problem, compressor problem etc…)

Question 9

The Generator Control Unit (GCU) provides for automatic starter cutoff when the engine reaches what % of Ng?

Answer 9

46%

Question 10

While initiating the prop overspeed governor test the prop stabilizes at 1810 rpm. Would you be willing to take off with this indication? Why or why not?

Answer 10

Yes. Limits are 1750 -+60…you are within limits.

Question 11

While flying to your destination the engine spools down to less than idle condition but is still running. What has probably occurred?

Answer 11

FCU Failure

Question 12

What corrective action should you take if the engine falls back to idle?

Answer 12

FCU Failure

• Power Idle
• Use EPL

Question 13

The EPL is connected by direct mechanical linkage to the main fuel metering valve located in the FCU, while using the EPL, what is the min and max Ng you may use during flight?

Answer 13

• Min = 65% Ng

- Max = 101.6% Ng

Question 14

Continued Flight in icing conditions is prohibited after encountering

Answer 14

• Airspeed of 120 KIAS cannot be maintained in level flight
• Airspeed decrease of 10 KIAS that cannot be prevented by increase to max continuous power
• MEA or MOCA on current leg falls into area “C” of icing service ceiling chart contained in Section 5 of Supplement S1 of the POH

Question 15

Engine:
What type?

Rated Horsepower at what RPM?

Number of fuel nozzles? Purpose and at what Ng?

Max ? Ng= ? RPM

Speed of the pwr turbine?

Do BETA and feathered engines go together? Why?

What does the torque meter use oil pressure for?

Where does P2.5 bleed air exist? What are a couple other things it can be used for?

What is P3 air used for? Main one?

Answer 15

• PT6A-114A, Reverse flow, free turbine, 3 stage axial, 1 stage centrifugal compressor 7:1 compression ratio
• Flat rated to 675 SHP at 1865 ft-lb. and 1900 RPM
• 14 simplex fuel nozzles, 10 operate for initial start; 14 after 30-35% Ng
• 101.6 Ng = 38,100 RPM
• Power turbine speed is 33,000
• Moving into BETA range while prop is feathered can damage prop-reversing linkage
• Torque meter uses a ratio of engine oil pressure to reduction gear oil pressure to operate
• P2.5 bleed air exits axial stage through compressor bleed valve, can be diverted to the cabin for supplemental heat or defog on ground only
• P3 bleed air is used for every other system on the plane

Question 16

What are the main reasons we use a lead acid battery?

Answer 16

use a lead acid battery?

1. For starting
2. Stand by pwr
   * 3. Absorb voltage spikes

Question 17

What Ng% are you looking for during start up?

Answer 17

Wait for 46% after initial startup, then once the annunciator turns off wait for 52% and turn off starter so the generator can take over.

Question 18

What % of the air intake is used within the turbine engine?

Answer 18

25% for air combustion
65% for cooling
5% for airframe servicing
5% secondary air sys; bearing seals

Question 19

What are the ITT probes used for and how many are there?

Answer 19

8 ITT probes are used to check the temp. of your inner turbine.

Question 20

How many fuel drains are there total, per wing?

Answer 20

9 total- 3 per wing

Question 21

Best Glide speeds (with pod)
8750
7500
6250
5000

Answer 21

8750- 95 kts
7500- 87 kts
6250- 79 kts
5000- 71 kts

Question 22

What are the four different electrical buses? Where is DC pwr routed through?

Answer 22

4 buses:

• Distribution
• Battery
• Optional Standby Alternator
• Avionics

DC pwr is routed through these four buses.

Question 23

What are the Takeoff limitations?
What does the special note of (1), (10), (2), (3), (7),
(9) signify?

Answer 23

Torque ft-lbs- 
1865 (1)
Max. ITT-
805 (10)
Gas Generator RPM % ng (2)-
101.6
Prop. RPM-
1900
Oil Press. PSIG (3)- 
85 to 105
Oil Temp. (7)-
10 to 99
SHP (9)-
675